adding 1 to every element with a number that is greater than 0

I have a matrix M =

 0     0     0     0     0     0     0     0
 0     0     0     0     0     0     6     0
 0     0     0     0     3     0     3     3
 0     0     0     9     9     6     9     6
 0     0     0     9     6     9     9     0
 0     0     0     0     6     3     0     0
 0     0     0     0     0     0     0     0
 0     0     0     0     0     0     0     0

and i want to add 1 to every element with a number greater that 0, 1-by-1 randomly x amount of time using matlab. Can anyone help me with this?